1910: Tsar Nicholas II heads an absolute monarchy that continues to resist the dilution of its power, despite recent constitutional reform, which for the first time legalize political parties and establish an elected parliament. His promise of civil rights goes unfulfilled, and growing public discontent is channeled into left-wing revolutionary associations which seek to overthrow the system.

1911-1916: A wave of workers' strikes gains momentum after the 1912 massacre of strikers at the Lena gold fields in Siberia. The Bolsheviks, a faction of the Russian Social Democratic Workers' Party, capitalize on the growing spirit of unrest and gain popular influence. Russia's entry into World War I leads to a surge in patriotism, which temporarily suspends public anger and disillusionment.

1917: A general strike, the "February revolution," forces Nicholas II's abdication and the monarchy's end. Power falls into two camps: a largely socialist provisional government and the Petrograd Soviet, a popularly elected assembly representing workers and soldiers in the capital. In October Vladimir Lenin and the Bolsheviks seize power, calling for the war's end and for a transfer of power to soviets.

1918-1920: The Bolsheviks allow countrywide elections for the Constituent Assembly, but close it down after winning only 20 percent of the vote. Based on the Central Committee and Politburo, the Communist Party becomes the Russian Soviet Federated Socialist Republic's political core. Promises of a new constitution are constantly delayed, but the imperial family's murder makes a return to monarchy impossible.

1921-1923: The USSR initially comprises the Soviets Russia, Byelorussia, Ukraine, and Caucasus, each with its own political organization but without real independence from the center. The civil war has heightened the absolute centralization of power. After less than a decade of independence, the Communist Party has suppressed and subsumed Russia's trade unions. Joseph Stalin becomes secretary general in 1922.

1924-1940: Following Lenin's death, Stalin argues against the need for international revolution for the USSR's survival; instead he aims for "socialism in one country." He moves against rivals in the Party, and by his 50th birthday in 1929, his dictatorship and cult of personality is fully established. Central planning is instituted, and the party reorganized to secure its total domination of the state.

1941-1945: During the second world war, the Communist Party and its centralized political structures prove highly effective in running the country. To raise morale and rally the people to Russia's defense for the "Great Patriotic War," Stalin moderates Soviet policy. Class warfare is temporarily forgotten, and the terror of mass purges brought to an end.

1946-1952: With the USSR's annexation of the countries of Eastern Europe comes the introduction of single-party regimes and Soviet-style socioeconomic reforms there. The prewar hostility of communist and capitalist worlds resumes. At home, victory establishes the legitimacy of the Soviet state in the eyes of many Russians. But having loosened the reins of power during the war, Stalin resumes total control.

1953-1963: By the time of Stalin's death, the political dictatorship has reached maturity, backed by the world's largest secret police, the gulag, aggressive censorship, and a vast military. Nikita Khrushchev denounces Stalinism, but the dictatorial machine remains intact, and his own cult of personality begins. His aggressive foreign policy results in the Berlin Wall's erection and the Cuban missile crisis.

1964-1984: On Khrushchev's death, the new regime revives the oligarchic principle of collective rule, but Leonid Brezhnev soon emerges as the most powerful leader. Brezhnev aims for stability on the international and domestic scene, but the brutal military suppression enforced after Czechoslovakia's uprising in 1968 offers stark proof of the limits of political reform possible within the USSR.

1985-1987: With perestroika, Gorbachev aims to restructure and improve the Soviet system without building a new one. Article 6 of the constitution, enshrining the Party's leading force in society, is removed. Gorbachev seeks to identify and end corruption endemic in political ranks. Internationally, he begins the retreat from the USSR's imperial ambitions as well as a policy of warm relations with the West.

1988-1990: Gorbachev's push to democratize the Soviet system leads to the creation of a Congress of People's Deputies. For the first time, real elections within the Party system take place with alternative candidates. The dramatic change in Soviet politics is marked by the lack of military response and the Party's impotence in the face of Poland's free elections and the fall of the Berlin Wall.

1991: Boris Yeltsin becomes president of the Russian Republic in the first-ever election for a Russian leader. After a political struggle, Gorbachev resigns as general secretary of the Communist Party of the USSR (CPSU), and the CPSU is subsequently made illegal. A loose Commonwealth of Independent States replaced the USSR, which is fragmenting along nationalist and ethnic lines.

1992-1995: Yeltsin's battle with a Communist-dominated Congress over a referendum for a new constitution ends with his dissolution of parliament. Communist hard-liners occupy the "White House" (parliament), but Yeltsin reasserts his position in a military clash, and the new constitution gives him sweeping powers. As Yeltsin's popularity wanes in the face of economic problems, that of the Communist Party grows.

1996-1999: Backed by Russia's increasingly powerful business tycoons, Yeltsin defeats Communist Gennadii Zyuganov and is reelected president of Russia in 1996. But Kremlin politics remain turbulent and unstable, especially when Yeltsin becomes seriously ill. His regime struggles to build an effective political administration and maintain control over local government.

2000-2001: Following Yeltsin's resignation, Vladimir Putin is elected president. He vows to strengthen Russia's standing in the world and increase the state's authority at home, while continuing to move toward a market economy. His authoritarian and reformist intentions raise questions, and his long-awaited government reform turns out to be little more than a Cabinet shuffle.

2002-2003: Vladimir Putin's consolidated power brings some political stability to Russia, but new anti-terror laws and measures to control the media raise fears of authoritarianism. Communists, splintered among several parties, attempt to reorganize to provide stronger opposition. Putin cements his alliance with the United States but stands firm with France and Germany in opposing the U.S. invasion of Iraq.